Method of applying adhesive strips to bags



2 Sheets-Sheet l April 9, 1968 H. a. MCGEE METHOD OF' APPLYING ADHESIVE STRIPS TO BAGS Filed sept. 27, 1965 ATTORNEYS April 9, 1968 H. B. MCGEE 3,377,186'

METHOD OF APPLYING ADHESIVE STRIPS TO lBAGSr Filed Sept. 2'7, 1965 2 Sheets-Sheet 2 INVENTOR HAROLD B. McGee Est/ ATTORNEYS United States Patent O 4 claims. (cl. 111-44) Claims This invention relates to the manufacture of paper bags and is particularly concerned with a method of applying strips of pressure-sensitive adhesive to the closure ends of large bags such as are used to cover mattresses.

While this invention is described hereinafter as being applicable to use with large paper bags, it will be understood that the method of applying strips of pressuresensitive adhesive as disclosed herein might be used to good advantage inthe manufacture of bags made of materials other than paper and in the manufacture of bags smaller in size than those specifically described and intended for wrapping large objects such as mattresses.

The purpose of applying strips of pressure-sensitive adhesive to the closure ends of bags is to provide simple means whereby the Ibags might be sealed once they have been lled. This particular type of sealing arrangement is known per se and includes a first strip of adhesive applied to the outer surface of one wall of the bag and a second strip applied to the inner surface of an opposed second wall, with both strips being positioned adjacent the intended closure end of the bag. In effecting closure, the forwardrnost end of the first wall is folded downwardly over the end of a received article andthe outer end of the second wall is folded upwardly and over the first wall as to bring the two strips of adhesive into contact to effect the seal.

In applying the strips, it has been the prior practice to effect the application by'hand. This process is time consuming, expensive and achieves inconsistent results.

In accord with the present invention, there is provided a method for semi-automatically applying strips of pressure-sensitive adhesive to the ends of bags wherein the process comprises the steps of laying the bags on a horizontal convey-or with the bags so positioned that they may be moved by the conveyor beneath stationary adhesive applying devices as to lay down strips of adhesive which are oriented on the bags in the desired manner, operating the conveyor to move the bags beneath said devices as to lay down a first strip on the outer surface of the top wall of the bag, subsequently lifting the top Wall as to expose the inner surface of the lower wall while continuing to move the bag as to lay down a second strip of adhesive on said inner surface, and finally moving the bag beneath radiant heaters while continuing to hold the top wall away from the lower as to expose both strips of adhesive to the curing effect of the heaters.

The invention will be more thoroughly understood from the following description of a preferred embodiment thereof as read in conjunction with the accompanying drawings.

In the drawings which illustrate an apparatus for carrying out this preferred embodiment of the invention,

FIG. l is a side elevation view of the apparatus;

FIG. 2 is a transverse elevation view taken along the line 2-2 of FIG. 1;

FIG. 3 is a transverse elevation view line 3 3 of FIG. 1;

FIG. 4 is a perspective view of the top surface of the conveyor forming part of the apparatus shown in FIG. 1 and having a series of bags at various stages of the method of the invention; and

taken along the FIG. 5 is a transverse elevation view taken along the line 5-5 of FIG. 1.

The apparatus for carrying out the method of the invention essentially consists of a first conveyor 10 for moving bags 12 beneath a pair of spaced spray guns 14 and 16, a second conveyor 18 carrying hooks 20 for holding the bags open as to expose the top surface of the lowermost wall, and a bank of radiant heaters 22 for curing the strips of adhesive applied by the guns 14 and 16.

The conveyor is of a type known heretofore consisting of a plurality of pivotally interconnected transversely extending platens engaged on at least tworrotatable sprockets -24 supported by a suitable frame 26. As the actual conveyor construction does not form part of this invention, it will be recognized that other suitable conveyors such as belt conveyors might be used.

The bags are laid on the conveyor with their longitudinal axes extending transverse to the direction of movement of the conveyor so that the applied adhesive strips will extend parallel with the ends of the bags. The bags essentially consist of a top wall 12a and a bottom wall 12b joined at their side edges. They are held on the conveyor by small hooks 21.

A-s the bags are moved by the conveyor, they trip a first microswitch 28 which sets the first spray gun 14 into operation so that a first strip of pressure-sensitive adhesive is sprayed onto the outer surface of top wall 12a. The operation of the first spray gun continues as long as the microswitch 28 is tripped -by the bag passing thereunder and immediately that the trailing side edge of the bag passes beneath the microswitch, operation of the spray gun ceases until the next bag moves into position to -retrip microswitch 28.

In the particular apparatus illustrated, the strips of adhesive are applied by spray guns but it will be appreciated that other types of strip applying devices might be used. Where spray guns are used, the adhesive is fed from suitable centaine-rs 30 through appropriate feed lines 32. The over spray of adhesive is carried away by Ventilating ducts 34.

Following application of the first adhesive strip to the bag, the latter is moved by the conveyor towards the secong spray gun 16. Between the two guns the operator engages the top wall 10a of the bag on hooks 36 carried by the second conveyor 18. The construction of these hooks can best be seen in FIGS, 3 and 5. They essentially consist of short curved arms 36a carried on the lower ends of rods 36h extending downwardly from the outer edges of the conveyor 18. To retain the bags on members 36a there is employed small leaf springs 36C which are turned upwardly at their lower ends as to permit ready entry and withdrawal from the pinching action between members 36a and the springs 36C. Conveyor 18 is driven at a speed which matches the speed of the first conveyor 10 as to retain the bag opening in a generally rectangular shape as shown in the drawings.

The two conveyors move the bags towards the second spray gun which is set into operation as the second microswitch 40 is tripped. As the gun 16 operates, it lays down a second strip of adhesive on the inner surface of the lower wall 10b, the gun being automatically shut off as the bag moves from under microswitch 40.

As a preferred final step, the bags having both adhesive strips in position are moved through a bank of heat lamps 22 with the bags being kept open as to expose both strips to the curing action of the heat. The heat lamps can be the usual infra-red which are commonly used in such applications but other heating devices would be apparent to those familiar with the art of curing adhesives.

The bags are moved through the heating zone as long as is required to cure the particular adhesive being used and are subsequently removed from both conveyors by a second operator.

What I claim as my invention is:

1. A method of applying strips of pressure-sensitive adhesive to a bag wherein the strips are positioned adjacent an intended closure end of the bag and extending substantially parallel to said end, a first strip being located on the outer surface of a first side of the bag and a second strip being located on the inner surface of a second opposed side of the bag whereby the adjacent end of the bag may be so folded to bring the strips into Contact as to effect closure of the bag, said method comprising the steps of placing the bag on a conveyor as to move the bag along a substantially horizontal path wherein an intended closure end of the bag is so located that it extends substantially parallel with the direction of movement of the conveyor, applying a first strip of pressuresensitive adhesive to the outer surface of a top wall of the bag adjacent said intended closure end by means of a stationary adhesive applying device as the bag is moved beneath said device by the conveyor, raising said top wall of the bag, and holding said top wall in its raised position while moving said bag beneath a second adhesive applying device as to deposit a second strip of adhesive on the upper surface of a lower wall of the bag adjacent said intended closure end.

2. A method as claimed in claim 1 including the further step of moving said bag through a heating zone after both said adhesive strips have been deposited, while maintaining said top wall in its raised position.

3. A method as claimed in clairn 1 in which said top wall is held in its raised position by means of a second conveyor positioned above said first conveyor and operated at the same speed as said second conveyor, said second conveyor carrying hooks on which said top wall is engaged.

4. A method as claimed in claim 1 including the step of setting said adhesive applying devices into operation automatically as said bag moves beneath said devices.

References Cited UNITED STATES PATENTS 3,269,087 8/1966 Cloud et al 229-69 X 3,035,938 5/1962 Schwinger 117-44 2,748,025 5/1956 Sackett et al. 117-44 2,715,493 8/1955 Vogt 229--69 RALPH S. KENDALL, Primary Examiner.

A. M. GRIMALDI, Assistant Examiner. 

1. A METHOD OF APPLYING STRIPS OF PRESSURE-SENSITIVE ADHESIVE TO A BAG WHEREIN THE STRIPS ARE POSITIONED ADJACENT AN INTENDED CLOSURE END OF THE BAG ND EXTENDING SUBSTANTIALLY PARALLEL TO SAID END, A FIRST STRIP BEING LOCATED ON THE OUTER SURFACE OF A FIRST SIDE OF THE BAG AND A SECOND STRIP BEING LOCATED ON THE INNER SURFACE OF A SECOND OPPOSED SIDE OF THE BAG WHEREBY THE ADJACENT END OF THE BAG MAY BE SO FOLDED TO BRING THE STRIPS INTO CONTACT AS TO EFFECT CLOSURE OF THE BAG, SAID METHOD COMPRISING THE STEPS OF PLACING THE BAG ON A CONVEYOR AS TO MOVE THE BAG ALONG A SUBSTANTALLY HORIZONTAL PATH WHEREIN AN INTENDED CLOSURE END OF THE BAG IS SO LOCATED THAT IT EXTENDS SUBSTANTIALLY PARALLEL WITH THE DIRECTION OF MOVEMENT OF THE CONVEYOR, APPLYING A FIRST STRIP OF PRESSURESENSITIVE ADHESIVE TO THE OUTER SURFACE OF A TOP WALL OF THE BAG ADJACENT SAID INTENDED CLOSURE END BY MEANS OF A STATIONARY ADHESIVE APPLYING DEVICE AS THE BAG IS MOVED BENEATH SAID DEVICE BY THE CONVEYOR, RAISING SAID TOP WALL OF THE BAG, AND HOLDING SAID TOP WALL IN ITS RAISED POSITION WHILE MOVING SAID BAG BENEATH A SECOND ADHESIVE APPLYING DEVICE AS TO DEPOSIT A SECOND STRIP OF ADHESIVE ON THE UPPER SURFACE OF A LOWER WALL OF THE BAG ADJACENT SAID INTENDED CLOSURE END. 